Question: Simplify the following expression: $k = \dfrac{20z}{30x - 5} - \dfrac{20y + 15x}{30x - 5}$ You can assume $x,y,z \neq 0$.
Explanation: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{20z - (20y + 15x)}{30x - 5}$ $k = \dfrac{20z - 20y - 15x}{30x - 5}$ The numerator and denominator have a common factor of $5$, so we can simplify $k = \dfrac{4z - 4y - 3x}{6x - 1}$